Apparatus for cathodic protection in an environment in which thin film corrosive fluids are formed and method thereof

ABSTRACT

An apparatus and method for cathodic protection in an environment where thin film corrosive fluids are formed is provided. The apparatus which protects from corrosion an object exposed to the thin film corrosive fluids, by artificially adjusting a potential of the object, comprises a DC power supply of which cathode is electrically connected to the object to be corrosion-protected, and an anodic assembly of which anode is electrically connected to the DC power supply. The anodic assembly includes an insulating filter member through which the corrosive fluids pass and which forms an accommodation space inside the insulating filter member, an anodic member accommodated in the insulating filter member, an electrode lead line which electrically connects the DC power supply to the anodic member, and an absorption conductive member which is accommodated in the insulating filter member to surround the circumference of the anodic member and absorbs the corrosive fluids flowing along an exposed surface of the object to be corrosion-protected.

This application is the U.S. national phase of international applicationPCT/KR2003/000299, filed 12 Feb. 2003, which designated the U.S. andclaims priority of KR 2002/0079430, filed 13 Dec. 2002, and KR2002/0079431, filed 13 Dec. 2003, the entire contents of each of whichare hereby incorporated by reference.

TECHNICAL FIELD

The present invention relates to an apparatus and method for cathodicprotection in an environment where thin film corrosive fluids areformed, and more particularly, to an apparatus and method which also cancorrosion-protect an object exposed to hot and humid gas-familycorrosive fluids.

BACKGROUND ART

Almost all metallic materials used in industries are extracted from rawores and restored into their original metallic states in time. Thus, astime passes, metallic materials used to construct industrial structuresor buildings react with an environment and are inevitably corroded oroxidized. This corrosion is mainly generated by electrochemicalreactions caused by the movement of electrons, and thus it is calledelectrochemical corrosion. Metallic structures are in corrosive batterystates while corrosion is progressing such that a corrosive potential isgenerated and a predetermined corrosive current flows through themetallic structures.

In general, corrosion protection is to eliminate or suppress one or moreconditions from main causes of corrosion. Electric protection is amethod for suppressing corrosion of facilities or structures mainly byartificially adjusting a potential or current of facilities orstructures requiring such protection. Electric protection includesanodic protection of anodizing an object to be corrosion-protected andcathodic protection of cathodizing the object to be corrosion-protected.In the case of anodic protection, when potential adjustment is notprecisely performed, corrosion may be accelerated. Thus, anodicprotection is used under certain conditions, and cathodic protection isusually used.

Cathodic protection is a method for preventing corrosion by artificiallyreducing the potential of an object to be corrosion-protected. Thecathodic protection is divided into a sacrificial anodic method and anexternal power method by the manner of applying an anticorrosivecurrent. In the sacrificial anodic method, metals that can be easilyionized are electrically connected in an electrolyte to act as an anode,thereby cathodizing the object to be corrosion-protected. In theexternal power method, a cathode (−) of a DC power supply or a rectifieris connected to the object to be corrosion-protected, and an anode (+)of the DC power supply or the rectifier is connected to a cathodemember, thereby obtaining an anticorrosive current.

Meanwhile, exhaust gases generated from combustion facilities such as asteam power plant and an incinerator, or sulfuric compounds contained ina hot and humid gas generated in a general chemical plant are changedinto a sulfurous acid gas by the following reaction.SO₂+O₂→SO₃+O

The sulfurous acid gas reacts with water below a dew point and isbalanced as H₂—SO₃—H₂SO₄. In addition, the sulfurous acid gas iscondensed on a metallic surface below a dew point comparatively lowerthan that of a flowing gas generated in bottoms, walls, or ceilings ofexhaust gas-family facilities and exists in the form of a thick film andthin film high-concentration sulfuric solution. The sulfuric solutioncauses serious corrosion of materials such as high alloy steel andcoating, on the basis of the period of starting and suspension offacilities. In addition, the sulfuric solution causes a harmful gas toleak out of corroded and damaged facilities and serious environmentalproblems. Thus, desulfurization facilities are made of high-pricedspecial anticorrosive alloy in consideration of corrosion. However, thedesulfurization facilities are easily corroded in a hot and humidenvironment which is a characteristic of condensed sulfuric acid andexhaust gas facilities. Due to frequent stoppage of facilities formaintenance, an economical efficiency in operation of facilities islowered, and for maintenance, high-priced special anticorrosive alloy orlining materials should be repeatedly used, yielding many additionalcosts. Thus, if the aforementioned electric protection is performed indesulfurization facilities, corrosion of desulfurization facilities canbe prevented. As a result, maintenance costs can be reduced, andinferior materials instead of high-priced special anticorrosive steel,can be used in desulfurization facilities. Thus, construction costs canalso be reduced.

However, a conventional apparatus and method for electric protection canbe used in various fields such as buried piping, ocean facilities,shipping, and cooling systems in a power plant. However, theconventional apparatus and method for electric protection can be usedonly in an environment where a sacrificial anodic member or an insolubleanodic member is completely dipped in corrosive fluids. Thus, theconventional apparatus and method for electric protection cannot be usedin an environment where thin film corrosive fluids are formed, like in aduct of desulfurization facilities. In addition, in the conventionalapparatus and method for electric protection, due to high electricconductivity like the case where corrosive fluids are a sulfuricsolution which is a waste solution flowing through a duct ofdesulfurization facilities, if electric protection is performed, theamount of consumption of an anticorrosive current increases. Inaddition, when an object to be corrosion-protected is used in anenvironment that severely varies in time and in addition the position ofthe object in the environment is not constant, it is not easy todetermine an anticorrosive current or a potential. As such, it isdifficult to use the conventional apparatus and method for the electricprotection of metallic structures such as a duct of desulfurizationfacilities.

DISCLOSURE OF THE INVENTION

The present invention provides an apparatus and method for cathodicprotection in an environment where thin film corrosive fluids areformed, which can supply a sufficient current required for electricprotection even when an object to be corrosion-protected continuouslycontacts corrosive fluids having strong corrosiveness and is notcompletely dipped in the corrosive fluids, like in a duct ofdesulfurization facilities, such that the life span of the object to becorrosion-protected is remarkably lengthened.

The present invention also provides a method for cathodic protection inan environment where thin film corrosive fluids are formed, which canperform electric protection economically and effectively even when dueto high electric conductivity, like in the case where corrosive fluidscontacting an object to be corrosion-protected are a sulfuric solutionwhich is a waste solution flowing through a duct of desulfurizationfacilities, if a conventional electric protection method is performed,the amount of consumption of an anticorrosive current increases, and theobject to be corrosion-protected is used in an environment that severelyvaries in time and in addition the position of the object in theenvironment is not constant.

According to one aspect of the present invention, there is provided anapparatus for cathodic protection in an environment where thin filmcorrosive fluids are formed, which protects from corrosion an objectexposed to the thin film corrosive fluids, by artificially adjusting apotential of the object, the apparatus comprising a DC power supply ofwhich cathode is electrically connected to the object to becorrosion-protected, and an anodic assembly of which anode iselectrically connected to the DC power supply. The anodic assemblyincludes an insulating filter member through which the corrosive fluidspass and which forms an accommodation space inside the insulating filtermember, an anodic member accommodated in the insulating filter member,an electrode lead line which electrically connects the DC power supplyto the anodic member, and an absorption conductive member which isaccommodated in the insulating filter member to surround thecircumference of the anodic member and absorbs the corrosive fluidsflowing along an exposed surface of the object to becorrosion-protected.

It is preferable that the anodic member includes a tubular anodic memberarranged in parallel to the exposed surface of the object to becorrosion-protected, and a plate-type anodic member combined with theouter circumference of the tubular anodic member. As such, the anodicmember has a sufficient large area to be in contact with the corrosivefluids.

Meanwhile, it is also preferable in installation rather than weldingthat the anodic assembly further includes an engagement combinationportion which holds an end of the electrode lead line and is engagedwith an inner circumference of the tubular anodic member so that the endof the electrode lead line contacts the inner circumference of thetubular anodic member.

Here, it is also preferable that the engagement combination portioncomprises a holder member which supports the end of the electrode leadline and has a large diameter part inserted into an inside of thetubular anodic member so that the end of the electrode lead linecontacts the inner circumference of the tubular anodic member, and asmall diameter part which has an outer diameter smaller than that of thelarge diameter part and in which a screw hole is formed, adiameter-enlarging member which is arranged to move forward and backwardto the large diameter part of the holder member on the outercircumference of the small diameter part of the holder member and has aplurality of elastic pieces arranged to be spaced apart from one anotherin a circumference direction on one of its ends, and a screw memberwhich is combined with a screw hole of the small diameter member of theholder member wherein the diameter-enlarging member is placed betweenthe screw member and the holder member, enlarges the diameter of theelastic pieces of the diameter-enlarging member by pressing thediameter-enlarging member toward the large diameter part and movingforward when rotating in an engagement direction of the screw hole, andis maintained to contact the inner circumference of the tubular anodicmember.

The anodic assembly further includes an insulating thin plate interposedbetween the surface of the object to be corrosion-protected and theinsulating filter member and in a partial region where a perforatedcontact hole is formed, thereby remarkably preventing from the anodicmember from contacting an exposed surface of the object to becorrosion-protected when the anodic member is broken.

The anodic assembly further comprises a support which is combined withthe exposed surface so that the support is stood and arranged on theexposed surface of the object to be corrosion-protected and whichsupports the anodic member to be spaced apart from the exposed surface,and an insulating connection member wherein a through hole through whichthe electrode lead line is passed is formed in a central region of theinsulating connection member in a lengthwise direction, and both ends ofwhich are detachably combined with ends of the support and the anodicmember.

Preferably, the insulating filter member is a non-woven fabric lining,and the absorption conductive member is coke breeze.

According to another aspect of the present invention, there is provideda method for cathodic protection in an environment where thin filmcorrosive fluids are formed, which protects from corrosion an objectexposed to the thin film corrosive fluids, by artificially adjusting apotential of the object, the method comprising providing an anodicassembly having an anodic member that is electrically connected to a DCpower supply, installing the anodic assembly on an exposed surface ofthe object to be corrosion-protected so that the anodic member is spacedapart from the exposed surface of the object to be corrosion-protected,and electrically connecting a cathode of the DC power supply to theobject to be corrosion-protected, forming a resin coating layer on theexposed surface by coating acid resisting and thermostable resin coatingmaterial, and flowing a current between the anodic member and thecathode.

Here, a painting layer is further formed between the exposed surface ofthe object to be corrosion-objected and the resin coating layer.

In addition, the anodic assembly further includes an insulating filtermember through which the corrosive fluids pass and which accommodatesthe anodic member in an accommodation space formed inside the insulatingfilter member, an electrode lead line which electrically connects the DCpower supply to the anodic member, and an absorption conductive memberwhich is accommodated in the insulating filter member to surround thecircumference of the anodic member and absorbs the corrosive fluidsflowing along an exposed surface of the object to becorrosion-protected, and further comprising absorbing the corrosivefluids flowing around the exposed surface of the object to becorrosion-protected into the absorption conductive member. As such, asufficient current required for electric protection can be supplied evenwhen the object to be corrosion-protected continuously contactscorrosive fluids having strong corrosiveness and is not completelydipped in the corrosive fluids.

Meanwhile, the object to be corrosion-protected is a duct ofdesulfurization facilities, and the corrosive fluids are a sulfuric acidsolution.

In addition, the resin coating material used for the resin coating layeris fluoric elastoma.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects and advantages of the present invention willbecome more apparent by describing in detail preferred embodimentsthereof with reference to the attached drawings in which:

FIG. 1 is a diagram schematically illustrating an apparatus for cathodicprotection in an environment where thin film corrosive fluids areformed, according to the present invention;

FIG. 2 is a cross-sectional view of an anodic assembly of FIG. 1;

FIG. 3 is a plan view of an anodic member of FIG. 2 for explaining thestate where a tubular anodic member and a plate-type anodic member arecombined with each other;

FIG. 4 illustrates the state of FIG. 2 where the anodic member iscombined with an engagement combination portion for connecting anelectrode lead line;

FIG. 5 is a cross-sectional view of a support of FIG. 2; and

FIG. 6 is a perspective view of an insulating connection member of FIG.2.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the present invention will be described in detail bydescribing preferred embodiments of the invention with reference to theaccompanying drawings.

FIG. 1 is a diagram schematically illustrating an apparatus for cathodicprotection in an environment where thin film corrosive fluids areformed, according to the present invention. As shown in FIG. 1, acathodic protection system 2 includes a DC power supply (not shown) ofwhich anode (+) is connected to an anodic assembly 1 and cathode (−) isconnected to an object 3 to be corrosion-protected, and a potentialmeasuring unit (not shown) that is electrically connected to a referenceelectrode 5 and the object 3 to be corrosion-protected. The cathodicprotection system 2 measures the potential of the object 3 to becorrosion-protected with respect to the reference electrode 5 using thepotential measuring unit, sets an output of the DC power supply based onthe measured potential, makes a predetermined anticorrosive current fromthe DC power supply to flow through the object 3 to becorrosion-protected via corrosive fluids 4 from an anodic member 22,which will be described later, of the cathodic assembly 1, therebyperforming corrosion protection of the object 3 to becorrosion-protected. Here, a resin coating layer 6 coated with fluoricelastoma or a ceramic-reinforced coating material is formed on anexposed surface of the object 3 to be corrosion-protected, exposed tothe corrosive fluids 4. The resin coating layer 6 basically protects theobject 3 to be corrosion-protected. When the resin coating layer 6 isdamaged by natural or mechanical deterioration, a damaged portion of theresin coating layer 6 is intensively protected by an anticorrosivecurrent, such that a small amount of current is consumed, the range ofthe anticorrosive current becomes still larger, and the object 3 to becorrosion-protected can be effectively corrosion-protected. Thus, evenwhen corrosive fluids are desulfurization facility condensed water, thatis, when pH value is very low, the concentration of sulfuric acid ishigh and electric conductivity is very high, electric protection can beeffectively performed.

For convenience of explanation, in FIG. 1, the anodic assembly 1 is notcompletely dipped in the corrosive fluids 4 but absorbs the corrosivefluids 4 by continuous contact of the corrosive fluids 4 flowing alongthe exposed surface of the object 3 to be corrosion-protected, and asufficient amount of the corrosive fluids 4 exists in the anodicassembly 1 and the object 3 to be corrosion-protected.

FIG. 2 is a cross-sectional view of an anodic assembly of FIG. 1. Asshown in FIG. 2, the anodic assembly 1 includes an insulating filtermember 10 through which corrosive fluids pass and which forms anaccommodation space inside the insulating filter member 10, an anodicmember 20 accommodated in the insulating filter member 10, an electrodelead line 25 which electrically connects a DC power supply (not shown)to the anodic member 20, an absorption conductive member 40 which isaccommodated in the insulating filter member 10 to surround thecircumference of the anodic member 20 and absorbs the corrosive fluidsflowing along the exposed surface 3 a of the object 3 to becorrosion-protected, an insulating thin plate 50 which is interposedbetween the surface of the object 3 to be corrosion-protected and theinsulating filter member 10, a support 60 which is combined with theexposed surface 3 a so that the support 60 is stood and arranged on theexposed surface 3 a of the object 3 to be corrosion-protected and whichsupports the anodic member 20 to be spaced apart from the exposedsurface 3 a, and an insulating connection member 70 which is detachablycombined with ends of the support 60 and the anodic member 20.

The insulating filter member 10 forms an accommodation space inside theinsulating filter member 10 and is a non-woven fabric lining. When thecorrosive fluids flow through the insulating filter member 10, thecorrosive fluids pass through the insulating filter member 10 and areabsorbed into the absorption conductive member 40. As such, theinsulating filter member 10 performs an insulation function.

FIG. 3 is a plan view of an anodic member of FIG. 2 for explaining thestate where a tubular anodic member and a plate-type anodic member arecombined with each other. Referring to FIG. 3 with FIG. 2, the anodicmember 20, made of titanium and coated with a precious metallic oxide,includes a tubular anodic member 21 having a tubular shape arrangedparallel to the exposed surface 3 a of the object 3 to becorrosion-protected, and a plate-type anodic member 23 having a plateshape combined with the outer circumference of the tubular anodic member21. The tubular anodic member 21 is combined with the electrode leadline 25 and the engagement combination portion 30 such that theelectrode lead line 25 is not exposed and is connected to the anodicmember 20. As the plate-type anodic member 23 has a sufficient largearea to be in contact with the corrosive fluids, the most amount of ananticorrosive current supplied to the plate-type anodic member 23 issupplied to the object 3 to be corrosion-protected via the corrosivefluids. Meanwhile, the length of the tubular anodic member 21 is largerthan that of the plate-type anodic member 23.

The electrode lead line 25 is connected to a DC power supply (not shown)and electrically connects the anodic member 20 to the DC power supply.The electrode lead line 25 is connected to the tubular anodic member 21by the engagement combination portion 30.

FIG. 4 illustrates the state of FIG. 2 where the anodic member iscombined with an engagement combination portion for connecting anelectrode lead line. As shown in FIG. 4, the engagement combinationportion 30 includes a holder member 31 which holds an end of theelectrode lead line 25, a diameter-enlarging member 33 having aplurality of elastic pieces 33 a arranged to be spaced apart from oneanother in a circumference direction on one of its ends, a screw member35 combined with the holder member 31 wherein the diameter-enlargingmember 33 is placed between the screw member 35 and the holder member31, and a washer member 34 arranged between the screw member 35 and thediameter-enlarging member 33.

The holder member 31 includes a large diameter part 31 a which supportsan end of the electrode lead line 25, a small diameter part 31 c whichhas an outer diameter smaller than that of the large diameter part 31 aand in which a screw hole 31 d is formed, and a slant part 31 b whichconnects the large diameter part 31 a to the small diameter part 31 c.The diameter-enlarging member 33 is arranged to move forward andbackward to the large diameter part 31 a of the holder member 31 on theouter circumference of the small diameter part 31 c of the holder member31. When the diameter-enlarging member 33 moves forward to the largediameter part 31 a of the holder member 31, an end placed at the elasticpieces 33 a is moved to the slant part 31 b, and thus, the diameter ofthe elastic pieces 33 a is enlarged. When the diameter of the elasticpieces 33 a of the diameter-enlarging member 33 is enlarged, the elasticpieces 33 a closely adhere to the inner circumference of the tubularanodic member 21 and is maintained to contact the tubular anodic member21. A forward-movement of the diameter enlarging member 33 to the holdermember 31 is performed when the screw member 35 is engaged with thescrew hole 31 d of the holder member 31 wherein the diameter-enlargingmember 33 is placed between the holder member 31 and the screw member35. The washer member 34 is provided between the screw member 35 and thediameter-enlarging member 33. When the diameter-enlarging member 33contacts the inner circumference of the tubular anodic member 21, theelectrode lead line 25 that perforates the holder member 31 ismaintained to contact the inner circumference of the tubular anodicmember 21. As such, the electrode lead line 25 can be convenientlyconnected to the anodic member 20 without welding. When a plurality ofthe anodic assemblies 1 are installed, a part of the electrode lead line25 contacts the tubular anodic member 21, and the other part of theelectrode lead line 25 extends, is pulled out toward the screw member35, and connected to a tubular anodic member of another anodic assembly.For this purpose, the shape of the diameter-enlarging member 33 and thescrew member 35 should be slightly modified. After the electrode leadline 25 is connected to the anodic member 20 with the engagementcombination portion 30, an inside of the tubular anodic member 21 iscompletely sealed with an acid resisting and thermostable sealing member(not shown).

The absorption conductive member 40, accommodated in the insulatingfilter member 10 to surround the anodic member 20, is coke breeze. Thecoke breeze can absorb corrosive fluids and is a conductive material.

The insulating thin plate 50 prevents the anodic member 20 from directcontacting the exposed surface 3 a of the object 3 to becorrosion-protected when the anodic member 20 is broken. The insulatingthin plate 50 is made of Teflon. A perforated contact hole 50 a isformed in a partial region of the insulating thin plate 50 so that thecorrosive materials absorbed into the absorption conductive member 40contacts the exposed surface 3 a of the object 3 to becorrosion-protected. Meanwhile, a cover 65 is installed on top of theinsulating filter member 10.

The support 60 is welded on the exposed surface 3 a of the object 3 tobe corrosion-protected, using the same material as metallic materialused for the object 3 to be corrosion-protected.

FIG. 5 is a cross-sectional view of a support of FIG. 2. As shown inFIG. 5, the support 60 includes an installation hole 62 where an end ofthe insulating connection member 70 is installed, and an insertion hole61 via which the end of the insulating connection member 70 is installedin the installation hole 62. A passage stub part 63 is formed on a lowerend of the support 60 so that the corrosive fluids are not interceptedby the support 60 and pass through the support 60. However, when thesupport 60 is installed on a sidewall of an exhaust gas duct, the lowerpart of the support 60 is completely intercepted so that the corrosivefluids do not flow down and leak out. Thus, the corrosive fluids flowingalong the wall of the exhaust gas duct stay in the support 60 such thatthe anodic member 20 sufficiently contacts the corrosive fluids andcurrent can be smoothly supplied.

FIG. 6 is a perspective view of an insulating connection member of FIG.2. As shown in FIG. 6, a protrusion 71 is provided at one side of theinsulating connection member 70. An end of the tubular anodic member 21is inserted in an opposite side to the protrusion 71 of the insulatingconnection member 70, and the protrusion 71 is engaged and installed inthe installation hole 62 of the support 60. Since the insulatingconnection member 70 is made of Teflon, the anodic member 20 ismaintained in an insulated state with the support 60 made of the samematerial as that of the object 3 to be corrosion-protected andsupported. The insulating connection member 70 may be made of plastics.

According to the above structure, a method for cathodic protection in anenvironment where thin film corrosive fluids are formed, according tothe present invention will be described below.

First, an anodic assembly 1 having an anodic member 20 electricallyconnected to a DC power supply is provided. The anodic assembly 1 mayuse only the anodic member 20 only if the anodic member 20 issufficiently buried in the corrosive fluids. However, in an environmentwhere thin film corrosive fluids 4 are formed, the anodic assembly 1should include an absorption conductive member 20 so that the corrosivefluids 4 flowing around the surface of the object 3 to becorrosion-protected is absorbed into the absorption conductive member 40and a sufficient amount of the corrosive fluids 4 exists between theanodic member 20 and the object 3 to be corrosion-protected.

Next, the anodic assembly 1 is installed on an exposed surface of theobject to be corrosion-protected, exposed to the corrosive fluids 4 sothat the anodic member 20 is spaced apart from the exposed surface ofthe object 3 to be corrosion-protected, and a cathode (−) of the DCpower supply is electrically connected to the object 3 to becorrosion-protected. The number and arrangement of the anodic assembly 1should be determined depending on the results of on-the-spot survey andreproduction experiment. Depending on spot conditions, the anodicassembly 1 may be installed by connecting a single electrode lead line25 or three or five electrode lead lines 25 to one another. When theobject 3 to be corrosion-protected is a duct, the anodic assembly 1 isinstalled inside the duct, and thus, a cathode of the DC power supply isconnected in a proper position outside the duct. In this case, theelectrode lead line 25 and the object 3 to be corrosion-protected areconnected by welding, and welded portions of the electrode lead line 25and the object 3 to be corrosion-protected are insulated.

Subsequently, a resin coating layer 6 is formed on the exposed surfaceof the object 3 to be corrosion-protected by coating acid resisting andthermostable resin coating material, e.g., fluoric elastoma orceramic-reinforced coating material in the present embodiment. In thisway, the fluoric resin is used in an environment where corrosion is veryserious, like in a duct of desulfurization facilities. The fluoric resinis a synthetic high molecular resin containing fluorine (F) in moleculesand has an excellent thermostable property, a medicine resistingproperty, an abrasion resisting property, an electric insulatingproperty, a high frequency property, an inadhesive low frictionalcoefficient, and a wet property. Preferably, the ceramic-reinforcedcoating material is a particle-reinforced composite coating materialwhich enables to have a resisting property to corrosion, erosion, andmedicines by mixing ceramic particles with acid resisting resin bymaximum 90%.

Next, the corrosive fluids flowing around the exposed surface of theobject 3 to be corrosion-protected are absorbed into the absorptionconductive member 40 of the anodic assembly 1. When the anodic member 20is dipped in the corrosive fluids, electric protection cannot bedirectly performed. However, when a thin film high-concentrationsulfuric acid solution is condensed on the surface of the object 3 to becorrosion-protected and remains thereon, like in the duct ofdesulfurization facilities, electric protection can be performed afterthe sulfuric acid solution is absorbed into the absorption conductivemember 40 of the anodic assembly 1 and stays around the anodic member20. In this case, the corrosive fluids absorbed into the absorptionconductive member 40 stay in a contact hole 25 a of the insulating thinplate 50 such that the anodic member 23 and the object 3 to becorrosion-protected are in contact with the corrosive fluids.

Last, an anticorrosive current flows between the anodic member 20 and acathode, thereby corrosion-protecting the object 3 to becorrosion-protected. However, the resin coating layer 6 basicallyprotects the object 3 to be corrosion-protected. Thus, when the resincoating layer 6 is formed on the entire exposed surface of the object 3to be corrosion-protected, the anticorrosive current does not flowbetween the anodic member 20 and a cathode. However, when the resincoating layer 6 is damaged by natural or mechanical deterioration, theanticorrosive current flows between the anodic member 20 and a cathode,and a damaged portion of the resin coating layer 6 is intensivelyprotected, thereby corrosion-protecting the object 3 to becorrosion-protected. In this case, damage of the resin coating layer 6may be detected by a potential measuring unit (not shown) that iselectrically connected to a reference electrode 5 and the object 3 to becorrosion-protected.

As described above, the anodic assembly 1 includes the absorptionconductive member 40 that can absorb the corrosive fluids flowingthrough the exposed surface of the object 3 to be corrosion-protected,such that a sufficient current required for electric protection can besupplied even when the object 3 to be corrosion-protected continuouslycontacts corrosive fluids having strong corrosiveness and is notcompletely dipped in the corrosive fluids, like in a duct ofdesulfurization facilities and the life span of the object 3 to becorrosion-protected can be remarkably lengthened.

In the above-described embodiment, the support 60 is welded on theexposed surface 3 a of the object 3 to be corrosion-protected, using thesame material as that of the object 3 to be corrosion-protected.However, the support 60 may be made of an insulating material and maycontact the exposed surface 3 a. In this case, the insulating filtermember 10 can be fixed by the support 60 without configuring theinsulating connection member 70.

In addition, in the above-described embodiment, the anodic assembly 1includes the support 60, the insulating thin plate 50, and the cover 65.However, this configuration is for stability and maintenance. Thus, eventhough the anodic assembly 1 does not include them, the effect of thepresent invention can be achieved.

In addition, in the above-described embodiment, the resin coating layer6 is formed after the anodic assembly 1 is installed and the cathode ofthe DC power supply is connected to the object 3 to becorrosion-protected. However, the order of the above two steps may bechanged. If the anodic member 20 is completely dipped in the corrosivefluids, the anodic assembly 1 may be composed of the anodic member 20.In this case, the step of absorbing the corrosive fluids into theabsorption conductive member 40 of the anodic assembly 1 may not beneeded.

In addition, in the above-described embodiment, a painting layer is notformed in the duct of desulfurization facilities which is the object 3to be corrosion-protected. However, even though the coating layer isformed in the duct of desulfurization facilities, the resin coatinglayer 6 is formed on the painting layer, and electric protection can beperformed.

INDUSTRIAL APPLICABILITY

As described above, in an apparatus and method for cathodic protectionin an environment where thin film corrosive fluids are formed accordingto the present invention, a sufficient current required for electricprotection can be supplied even when an object to be corrosion-protectedcontinuously contacts corrosive fluids having strong corrosiveness andis not completely dipped in the corrosive fluids, like in a duct ofdesulfurization facilities, such that the life span of the object to becorrosion-protected is remarkably lengthened.

In addition, in a method for cathodic protection in an environment wherethin film corrosive fluids are formed according to the presentinvention, electric protection can be economically and effectivelyperformed even when due to high electric conductivity, like in the casewhere corrosive fluids contacting an object to be corrosion-protectedare a sulfuric solution which is a waste solution flowing through a ductof desulfurization facilities, if a conventional electric protectionmethod is performed, the amount of consumption of an anticorrosivecurrent increases, and the object to be corrosion-protected is used inan environment that severely varies in time and in addition the positionof the object in the environment is not constant.

While this invention has been particularly shown and described withreference to preferred embodiments thereof, it will be understood bythose skilled in the art that various changes in form and details may bemade therein without departing from the spirit and scope of theinvention as defined by the appended claims.

1. An apparatus for cathodic protection in an environment where thinfilm corrosive fluids are formed, which protects from corrosion anobject exposed to the thin film corrosive fluids, by artificiallyadjusting a potential of the object, the apparatus comprising: a DCpower supply of which cathode is electrically connected to the object tobe corrosion-protected; and an anodic assembly of which anode iselectrically connected to the DC power supply; wherein the anodicassembly includes an insulating filter member through which thecorrosive fluids pass and which forms an accommodation space inside theinsulating filter member, an anodic member accommodated in theinsulating filter member, an electrode lead line which electricallyconnects the DC power supply to the anodic member, and an absorptionconductive member which is accommodated in the insulating filter memberto surround the circumference of the anodic member and absorbs thecorrosive fluids flowing along an exposed surface of the object to becorrosion-protected.
 2. The apparatus of claim 1, wherein the anodicmember includes a tubular anodic member arranged in parallel to theexposed surface of the object to be corrosion-protected.
 3. Theapparatus of claim 2, wherein the anodic member further includes aplate-type anodic member combined with the outer circumference of thetubular anodic member.
 4. The apparatus of claim 2, wherein the anodicassembly further includes an engagement combination portion which holdsan end of the electrode lead line and is engaged with an innercircumference of the tubular anodic member so that the end of theelectrode lead line contacts the inner circumference of the tubularanodic member.
 5. The apparatus of claim 4, wherein the engagementcombination portion comprises: a holder member which supports the end ofthe electrode lead line and has a large diameter part inserted into aninside of the tubular anodic member so that the end of the electrodelead line contacts the inner circumference of the tubular anodic member,and a small diameter part which has an outer diameter smaller than thatof the large diameter part and in which a screw hole is formed; adiameter-enlarging member which is arranged to move forward and backwardto the large diameter part of the holder member on the outercircumference of the small diameter part of the holder member and has aplurality of elastic pieces arranged to be spaced apart from one anotherin a circumference direction on one of its ends; and a screw memberwhich is combined with a screw hole of the small diameter member of theholder member wherein the diameter-enlarging member is placed betweenthe screw member and the holder member, enlarges the diameter of theelastic pieces of the diameter-enlarging member by pressing thediameter-enlarging member toward the large diameter part and movingforward when rotating in an engagement direction of the screw hole, andis maintained to contact the inner circumference of the tubular anodicmember.
 6. The apparatus of claim 1, wherein the anodic assembly furtherincludes an insulating thin plate interposed between the surface of theobject to be corrosion-protected and the insulating filter member and ina partial region where a perforated contact hole is formed.
 7. Theapparatus of claim 1, wherein the anodic assembly further comprises: asupport which is combined with the exposed surface so that the supportis stood and arranged on the exposed surface of the object to becorrosion-protected and which supports the anodic member to be spacedapart from the exposed surface; and an insulating connection memberwherein a through hole through which the electrode lead line is passedis formed in a central region of the insulating connection member in alengthwise direction, and both ends of which are detachably combinedwith ends of the support and the anodic member.
 8. The apparatus ofclaim 1, wherein the insulating filter member is a non-woven fabriclining, and the absorption conductive member is coke breeze.
 9. A methodfor cathodic protection in an environment where thin film corrosivefluids are formed, which protects from corrosion an object exposed tothe thin film corrosive fluids, by artificially adjusting a potential ofthe object, the method comprising: providing an anodic assembly havingan anodic member that is electrically connected to a DC power supply;installing the anodic assembly on an exposed surface of the object to becorrosion-protected so that the anodic member is spaced apart from theexposed surface of the object to be corrosion-protected, andelectrically connecting a cathode of the DC power supply to the objectto be corrosion-protected; forming a resin coating layer on the exposedsurface by coating acid resisting and thermostable resin coatingmaterial; and flowing a current between the anodic member and thecathode.
 10. The method of claim 9, wherein a painting layer is furtherformed between the exposed surface of the object to becorrosion-objected and the resin coating layer.
 11. The method of claim9, wherein the anodic assembly further includes an insulating filtermember through which the corrosive fluids pass and which accommodatesthe anodic member in an accommodation space formed inside the insulatingfilter member, an electrode lead line which electrically connects the DCpower supply to the anodic member, and an absorption conductive memberwhich is accommodated in the insulating filter member to surround thecircumference of the anodic member and absorbs the corrosive fluidsflowing along an exposed surface of the object to becorrosion-protected, and further comprising absorbing the corrosivefluids flowing around the exposed surface of the object to becorrosion-protected into the absorption conductive member.
 12. Themethod of claim 9, wherein the object to be corrosion-protected is aduct of desulfurization facilities, and the corrosive fluids are asulfuric acid solution.
 13. The method of claim 9, wherein the resincoating material used for the resin coating layer is fluoric elastoma.